The basic rules that govern the organization, structure and function of mammalian chromosomes remain unclear. Understanding the structure-function relationship which underlies transcriptional activation, replication, recombination and repair of chromosomes is a crucial component of chromosomal research. We propose to extend our biochemical and biophysical studies on chromatin reconstituted with histones of varying levels of acetylation, minor histone variants associated with sperm chromatin, and protamine to include small angle x-ray scattering studies on these particles. These experiments will determine the role of these chromatin variables in the maintenance and stabilization of basic chromatin structure.